When obedience becomes our goal, it is no longer an irritation; instead of stumbling block, it becomes a building block." 

~~~ James E. Faust~~~

This quote is saying that instead of not being obedience and being a stumbling block it becomes a building which means that there aren't any blocks to drag you down but instead there are blocks that give you more opportunities that won't drag you down. For example there are so many stumbling blocks in your life if your aren't obedience you'll have many stumbling blocks because you aren't setting obedience as your goal and it becomes an irritation for you. If you set obedience as your goal it won't be an irritation for you but a building block you will set new goals in life do new things achieve  new things. When obedience is your daily goal and you achieve it you a building new building blocks a lots of them as well. If you have many building blocks then you are being obedient and doing what your supposed to be doing.